Accompanying the recent increase in the use of data processing systems, and the extension of business hours or the shift to 24-hour uninterrupted operation, it has become difficult to allocate time, after stopping execution of an application for updating data, for execution of an application for processing data in a static state in which no data updating operation is being performed. It should be noted that an application can, for example, be a computer program or any other such means for performing a particular processing on data. The application for processing data could, for example, be a computer program for taking a backup copy, executing statistical processing on daily business results, etc. Hence, apparatus have been sought for simultaneously executing an application for performing a data updating operation and an application that must be executed in the state in which no data updating operation has been performed.
To solve the above Japanese Patent Laid-open No. Hei 5-94265 proposes a mechanism in which, in a multiple-writing filing system, the multiple-writing configuration is cleared and an application is allowed to update one of the cleared devices. The controller takes a backup copy of the other device in a static state in which no updating operation is being performed.
Japanese Patent Laid-open No. Hei 6-44010 proposes that all or part of a data set to be affected by an updating operation is written to a subsystem memory. The update is then written to the subsystem memory to complete the updating operation. In response to an input request from the backup copy, the data in the not-updated portion is input from the original data set, and the data in the updated portion is input from the subsystem memory.
The method disclosed in Japanese Patent Laid-open No. Hei 5-94265 does not consider a situation in which an application other than an application taking a backup copy references static data that has not been updated. Therefore, this conventional arrangement must execute an application that requires static data after storing a backup copy taken by the backup copy taking application into an external storage device to maintain the logical integrity of the data.
The method disclosed in Japanese Patent Laid-open No. Hei 6-44010 does not consider application of the disclosed technology to any type of application. Therefore, this conventional arrangement needs to be aware of whether an area for data input/output operations by each application requiring application of the disclosed technology has been updated or not. This presents problems of making applications complicated and pushes up the cost of the entire system.